The present invention relates to the movement of bulk materials, and more particularly, pertains to moving and stacking material, such as ore, coal, granite, clay, salt, and potash, generally referred to herein as “aggregate”, by mobile belt conveyor modules.
The present invention is concerned with depositing aggregate into piles, and more particularly is an improved method for depositing aggregate into multi-lift dump sites, such as heap leach stacks, waste dump sites, or material dump sites, for example.
In the past, very long, endless conveyor belt assemblies have been used for transporting loose particulate material over long distances. Bridge conveyors or mobile stacking conveyors have also been used. One of the problems with the conveyor systems of the prior art is that such systems take time to move any appreciable distance when a new stack is to be started. This is especially true when stacking aggregate ore which is to be subjected to heap leach processes used, for example, to extract copper or gold from the stacked piles of aggregate or leach pads.
In today's world, mining is a basic industry in a global economy. Thus, regardless of the site of the mining or leaching operation, it must be conducted in a manner that minimizes capital costs, minimizes operating costs, and minimizes the delay time between stacking heaps and recovering the metals or mineral of interest.
Prior art multiple lift stacking systems using bridges, with either advance or retreat stacking, require considerable down time, a great deal of additional earth work effort, and a considerable amount of labor to extend and retract the overland conveyor used in the process. The prior art stacking processes delay recovery of the metals or minerals of interest from the aggregate. In an ongoing leaching operation, for example, a major concern is to leach the newly stacked aggregate immediately. Thus, at the completion of any lift, a complete leach cycle time is scheduled before stacking the next lift so that the material can be leached to full economic advantage at each lift.
These concerns, in general, require movement of the prior art systems that could be both wasteful and unnecessary.
A prior art attempt to solve such a problem is described in U.S. Pat. No. 6,085,890 granted Jul. 11, 2000 to Ronald R. Kelly, et al. for Heap Leach Stacking Process. However, even this approach requires down time, a shortcoming which the present invention overcomes.